Journal articles: 'Polyhydroxyalkanoates (PHA)'

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Alamgeer, Mohammad. "Polyhydroxyalkanoates (PHA) genes Database." Bioinformation 15, no. 1 (January 31, 2019): 36–39. http://dx.doi.org/10.6026/97320630015036.

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Możejko-Ciesielska, Justyna, and Agnieszka Mostek. "Time-Course Proteomic Analysis of Pseudomonas putida KT2440 during Mcl-Polyhydroxyalkanoate Synthesis under Nitrogen Deficiency." Polymers 11, no. 5 (April 26, 2019): 748. http://dx.doi.org/10.3390/polym11050748.

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Medium-chain-length polyhydroxyalkanoates (mcl-PHAs) have gained great attention as a new green alternative to petrochemical-derived polymers. Due to their outstanding material properties they can be used in a wide range of applications. Pseudomonas putida KT2440 is a metabolically versatile producer of mcl-polyhydroxyalkanoates. Although the metabolism of polyhydroxyalkanoate synthesis by this bacterium has been extensively studied, the comparative proteome analysis from three growth stages of Pseudomonas putida KT2440 cultured with oleic acid during mcl-PHA synthesis has not yet been reported. Therefore; the aim of the study was to compare the proteome of Pseudomonas putida KT2440 at different time points of its cultivation using the 2D difference gel electrophoresis (2D-DIGE) technique. The analyses showed that low levels of a nitrogen source were beneficial for mcl-PHA synthesis. Proteomic analysis revealed that the proteins associated with carbon metabolism were affected by nitrogen starvation and mcl-PHA synthesis. Furthermore, the induction of proteins involved in nitrogen metabolism, ribosome synthesis, and transport was observed, which may be the cellular response to stress related to nitrogen deficiency and mcl-PHA content in bacterial cells. To sum up; this study enabled the investigators to acquire a better knowledge of the molecular mechanisms underlying the induction of polyhydroxyalkanoate synthesis and accumulation in Pseudomonas putida KT2440 that could lead to improved strategies for PHAs in industrial production.

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Ferdiansyah, M. Khoiron. "Pengaruh Oksigen Pada Akumulasi Poly Hydroxy Alkanoates (PHA)." AGRISAINTIFIKA: Jurnal Ilmu-Ilmu Pertanian 1, no. 1 (June 29, 2017): 15. http://dx.doi.org/10.32585/ags.v1i1.34.

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Polyhydroxyalkanoates (PHA) adalah salah satu contoh dari bioplastik. PHA disintesis oleh bakteri sebagai karbon atau komponen simpanan energi ketika jumlah intake karbon berlebihan dan beberapa nutrisi seperti nitrogen, phospor, dan oksigen dalam kondisi yang terbatas. Pemberian aerasi oksigen sangat mempengaruhi produksi dan akumulasi PHA. Tingkat aerasi oksigen yang rendah akan meningkatkan konsentrasi PHA. Penetapan suplai oksigen pada batas level tertentu yang tepat akan dapat meningkatkan produktivitas atau akumulasi PHA, tanpa mengganggu pertumbuhan mikroorganismeKata kunci: polyhydroxyalkanoates, bioplastik, oksigen, bakteri

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Zhang, Junyu, Ekaterina I. Shishatskaya, Tatiana G. Volova, Luiziana Ferreira da Silva, and Guo-Qiang Chen. "Polyhydroxyalkanoates (PHA) for therapeutic applications." Materials Science and Engineering: C 86 (May 2018): 144–50. http://dx.doi.org/10.1016/j.msec.2017.12.035.

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Puppi, Dario, Gianni Pecorini, and Federica Chiellini. "Biomedical Processing of Polyhydroxyalkanoates." Bioengineering 6, no. 4 (November 29, 2019): 108. http://dx.doi.org/10.3390/bioengineering6040108.

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The rapidly growing interest on polyhydroxyalkanoates (PHA) processing for biomedical purposes is justified by the unique combinations of characteristics of this class of polymers in terms of biocompatibility, biodegradability, processing properties, and mechanical behavior, as well as by their great potential for sustainable production. This article aims at overviewing the most exploited processing approaches employed in the biomedical area to fabricate devices and other medical products based on PHA for experimental and commercial applications. For this purpose, physical and processing properties of PHA are discussed in relationship to the requirements of conventionally-employed processing techniques (e.g., solvent casting and melt-spinning), as well as more advanced fabrication approaches (i.e., electrospinning and additive manufacturing). Key scientific investigations published in literature regarding different aspects involved in the processing of PHA homo- and copolymers, such as poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), are critically reviewed.

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Valentin, Henry E., and Douglas Dennis. "Application of an optimized electroporation procedure for replacement of the polyhydroxyalkanoate synthase I gene inNocardia corallina." Canadian Journal of Microbiology 42, no. 7 (July 1, 1996): 715–19. http://dx.doi.org/10.1139/m96-098.

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To develop a system for gene replacement in Nocardia corallina, a protocol for electroporation was optimized by systematic alterations of growth conditions, field strength, time constant and the electroporation buffer. Transformation efficiencies of 0.5 × 106–3 × 106transformants/μg plasmid DNA were obtained routinely. The gene encoding the polyhydroxyalkanoate (PHA) synthase I of N. corallina was cloned and interrupted by insertion of a kanamycin-resistance gene. The resulting plasmid was introduced into N. corallina by electroporation to inactivate the wild-type gene by homologous recombination. Kanamycin-resistant clones were screened by Southern hybridization for the absence of the wild-type gene and analyzed for PHA accumulation.Key words: gene replacement, Nocardia, polyhydroxyalkanoates (PHAs).

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Dienye, B. N., G. O. Abu, and O. K. Agwa. "Screening and Biochemical Characterization of Indigenous Polyhydroxyalkanoates Producing Bacteria." Journal of Advances in Microbiology 23, no. 2 (February 21, 2023): 43–55. http://dx.doi.org/10.9734/jamb/2023/v23i2709.

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Exploration for promising polyhydroxyalkanoates (PHA) producers is a continuous process as effort to mitigate the accumulation of synthetic plastic is on the rise. The present study focuses on isolation of indigenous polyhydroxyalkanoates producing bacteria from soil, waste water effluent and organic waste sample of Obio-Akpor, LGA. Screening of the selected bacteria isolates for polyhydroxyalkanoates production was based on viable plate method followed by microscopic visualization using Sudan black B. The PHA producing abilities of the selected isolates were estimated by gravimetric method and the positive isolates were detected for the presence of PHA synthase gene and identified up to genus level. Results revealed that out of 106 isolates, 55 were suspected to accumulate PHA after screening and produced PHA in the range of 0.2-1.1 g/L. Six potential isolates produced highest PHA yield and their phaC genes were successfully amplified from genomic DNA. Based on morphological, cultural and biochemical characteristics, the six isolates were tentatively identified to the genus Bacillus sp, Lysinibacillus sp and Pseudomonas sp. The result of the present study indicated that these bacterial isolates have the potential of producing PHA and their potential harnessed for future purposes.

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Idris, Shehu, Rashidah Abdul Rahim, Ahmad Nazri Saidin, and Amirul Al-Ashraf Abdullah. "Bioconversion of Used Transformer Oil into Polyhydroxyalkanoates by Acinetobacter sp. Strain AAAID-1.5." Polymers 15, no. 1 (December 26, 2022): 97. http://dx.doi.org/10.3390/polym15010097.

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In this research, the utilisation of used transformer oil (UTO) as carbon feedstock for the production of polyhydroxyalkanoate (PHA) was targeted; with a view to reducing the environmental challenges associated with the disposal of the used oil and provision of an alternative to non-biodegradable synthetic plastic. Acinetobacter sp. strain AAAID-1.5 is a PHA-producing bacterium recently isolated from a soil sample collected in Penang, Malaysia. The PHA-producing capability of this bacterium was assessed through laboratory experiments in a shake flask biosynthesis under controlled culture conditions. The effect of some biosynthesis factors on growth and polyhydroxyalkanoate (PHA) accumulation was also investigated, the structural composition of the PHA produced by the organism was established, and the characteristics of the polymer were determined using standard analytical methods. The results indicated that the bacteria could effectively utilise UTO and produce PHA up to 34% of its cell dry weight. Analysis of the effect of some biosynthesis factors revealed that the concentration of carbon substrate, incubation time, the concentration of yeast extract and utilisation of additional carbon substrates could influence the growth and polymer accumulation in the test organism. Manipulation of culture conditions resulted in an enhanced accumulation of the PHA. The data obtained from GC-MS and NMR analyses indicated that the PHA produced might have been composed of 3-hydroxyoctadecanoate and 3-hydroxyhexadecanoate as the major monomers. The physicochemical analysis of a sample of the polymer revealed an amorphous elastomer with average molecular weight and polydispersity index (PDI) of 110 kDa and 2.01, respectively. The melting and thermal degradation temperatures were 88 °C and 268 °C, respectively. The findings of this work indicated that used transformer oil could be used as an alternative carbon substrate for PHA biosynthesis. Also, Acinetobacter sp. strain AAAID-1.5 could serve as an effective agent in the bioconversion of waste oils, especially UTO, to produce biodegradable plastics. These may undoubtedly provide a foundation for further exploration of UTO as an alternative carbon substrate in the biosynthesis of specific polyhydroxyalkanoates.

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Tarrahi, Roshanak, Zahra Fathi, M. Özgür Seydibeyoğlu, Esmail Doustkhah, and Alireza Khataee. "Polyhydroxyalkanoates (PHA): From production to nanoarchitecture." International Journal of Biological Macromolecules 146 (March 2020): 596–619. http://dx.doi.org/10.1016/j.ijbiomac.2019.12.181.

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Pernicova, Iva, Dan Kucera, Ivana Novackova, Juraj Vodicka, Adriana Kovalcik, and Stanislav Obruca. "Extremophiles - Platform Strains for Sustainable Production of Polyhydroxyalkanoates." Materials Science Forum 955 (May 2019): 74–79. http://dx.doi.org/10.4028/www.scientific.net/msf.955.74.

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Polyhydroxyalkanoates (PHA) are biodegradable polyesters, which are produced by various bacteria including numerous halophiles. Employment of halophilic strain for PHA production brings numerous benefits such as robustness of the process against contamination by ubiquitous mesophiles or possibility to isolate polymer from bacterial biomass via hypotonic lysis. In this work, we screened three moderate halophiles – Halomonas halophila, Halomonas organivorans and Halomonas salina for the presence of phaC gene encoding for PHA synthase and, subsequently, we have investigated their PHA production potential on various sugars. Among tested strains, H. organivorans demonstrated the extraordinary capacity of PHA production in particular on galactose and mannose since on these saccharides PHA content in dried bacterial cells reached 83 and 90 wt. % on mannose and galactose, respectively. Therefore, H. organivoras can be considered being promising PHA producing strain in particular suitable for the valorization of lignocellulose materials rich in galactomannans such as spent coffee grounds.

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Matias, Fernanda, Diego Bonatto, Gabriel Padilla, Maria Filomena de Andrade Rodrigues, and João Antonio Pêgas Henriques. "Polyhydroxyalkanoates production by actinobacteria isolated from soil." Canadian Journal of Microbiology 55, no. 7 (July 2009): 790–800. http://dx.doi.org/10.1139/w09-029.

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Polyhydroxyalkanoates (PHAs) are biodegradable and renewable polymers produced by a wide range of bacterial groups. New microbial bioprospection approaches have become an important way to find new PHA producers and new synthesized polymers. Over the past years, bacteria belonging to actinomycetes group have become known as PHA producers, such as Nocardia and Rhodococcus species, Kineosphaera limosa Liu et al. 2002, and, more recently, Streptomyces species. In this paper, we disclose that there are more actinobacteria PHA producers in addition to the genera cited. Some unusual genera, such as Streptoalloteichus , and some genera frequently present in soil, such as Streptacidiphilus , have been found. Thirty-four isolates were able to accumulate poly(3-hydroxybutyrate) and a number of these have traces of poly(3-hydroxyvalerate) when cultivated on glucose or glucose and casein as carbon source. Furthermore, some strains showed traces of medium chain length PHA. Transmission electron microscopy demonstrated that the PHA accumulation occurs in hyphae and spores.

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Afghan, Inzer Gul, Ajmal Hashmi, and Abdul Ali. "General Overview of Previous Advances on Polyhydroxyalkanoates (PHA) Synthesis by Microorganism Utilizing Different Waste Carbon Sources." Journal for Research in Applied Sciences and Biotechnology 1, no. 4 (November 13, 2022): 176–80. http://dx.doi.org/10.55544/jrasb.1.4.25.

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This review paper denotes recent advances of Polyhydroxyalkanoates (PHA), derived from bacterial fermentation of sugars or lipids. Polyhydroxyalkanoates (PHA) are biodegradable polyesters, (PHA) has many hydroxyl groups depend on carbon sources. This study gives overview of recent research dealing with PHA synthesis, utilizing various carbon sources producing biodegradable polymers, degrading of PHA by microorganism to water and carbon dioxide found in soil, sewage and water, therefore, PHA Production increased under salty medium such as sodium chloride, bioplastic was characterized by FTIR, DSC, TGA, and NMR. recent studies on contaminant treatment, tissue engineering and fermentation strategies can give comprehension for researchers to design production of bioplastics from waste carbon sources. Also cost effective PHA synthesis, this review explores beneficial information about the limit affiliate with the tolerable PHA synthesis utilizing different waste carbon sources. various great advances have been generated: different wastes as raw material, various extraction pathways, and meet design of bioplastic. This review paper resumed the scientific and technological improvement of PHA through their discovery in 1888 up to their recent applications and most current commercial utilization.

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Zhang, Yan Ping. "The Influence of Different Carbon Sources for Polyhydroxyalkanoates Storage." Advanced Materials Research 1088 (February 2015): 587–90. http://dx.doi.org/10.4028/www.scientific.net/amr.1088.587.

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The influence of different carbon sources such as glucose, sodium acetate, sodium propionate and ethanol for polyhydroxyalkanoates (PHA) storage were studied in details. It was shown that both the cell content and composition of PHA synthesized by microorganisms in activated sludge were different when different carbon sources were used. PHB (polyhydroxybutyrate) was the main PHA if sodium acetate was used as carbon source, while PHV (polydroxyvalerate) become the main PHA when sodium propionate was used. Sodium acetate and sodium propionate as carbon source had higher PHA production, which reached to 40.89% and 40.96% sludge dry weight, respectively . When ethanol used as carbon source, PHA content was 25.69% sludge dry weight. The minimal PHA storage was 20.14% sludge dry weight when glucose was used.

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Koller, Martin, and Anindya Mukherjee. "Polyhydroxyalkanoates – Linking Properties, Applications and End-of-life Options." Chemical & biochemical engineering quarterly 34, no. 3 (2020): 115–29. http://dx.doi.org/10.15255/cabeq.2020.1819.

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When it comes to “bioplastics”, we currently notice an immense complexity of this topic, and, most of all, a plethora of contradictory legislations, which confuses or even misleads insufficiently informed consumers. The present article therefore showcases microbial polyhydroxyalkanoate (PHA) biopolyesters as the prime class of “bioplastics” sensu stricto. In particular, biodegradability of PHA as its central benefit in elevating the current plastic waste scenario is elaborated on the biochemical basis: this covers aspects of the enzymatic machinery involved both in intra- and extracellular PHA degradation, and environmental factors impacting biodegradability. Importantly, PHA degradability is contextualized with potential fields of application of these materials. It is further shown how the particularities of PHA in terms of feedstocks, mode of synthesis, degradability, and compostability differ from other polymeric materials sold as “bioplastics”, highlighting the unique selling points of PHA as “green” plastic products in the circular economy. Moreover, current standards, norms, and certificates applicable to PHA are presented as basis for a straight-forward, scientifically grounded classification of “bioplastics”.

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Sehgal, Rutika, and Reena Gupta. "Characterization of medium chain length polyhydroxyalkanoates from Priestia megaterium POD1." Research Journal of Chemistry and Environment 26, no. 10 (September 25, 2022): 46–54. http://dx.doi.org/10.25303/2610rjce046054.

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Polyhydroxyalkanoate (PHA) is the most promising solution to the major ecological problem of plastic accumulation. It is synthesized by bacteria when there is limited availability of nutrients as intracellular granules. The biodegradable and biocompatible properties of PHA make it highly demanding in the biomedical and agricultural field. Among PHA, medium chain length (mcl) PHA has shown more interest because of its favorable properties like having more viscous material, low crystallinity degrees, low melting temperature and low glass transition temperatures for many applications which require flexible material. Therefore, we have isolated a bacterial strain, Priestia megaterium POD1 which can produce mcl PHA very efficiently. The isolate was confirmed to have phaC gene responsible for PHA synthesis. The PHA extracted from the isolate was characterized by FTIR, NMR and GC-MS which revealed the extracted polymer to be a mixture of different mcl PHA. Hence, the present study would provide a potential mcl PHA producer which can be explored for its properties which are demanding in present bioplastic market.

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Chen, Guo-Qiang, Xiao-Ran Jiang, and Yingying Guo. "Synthetic biology of microbes synthesizing polyhydroxyalkanoates (PHA)." Synthetic and Systems Biotechnology 1, no. 4 (December 2016): 236–42. http://dx.doi.org/10.1016/j.synbio.2016.09.006.

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Chen, Guo-Qiang, and Xiao-Ran Jiang. "Engineering bacteria for enhanced polyhydroxyalkanoates (PHA) biosynthesis." Synthetic and Systems Biotechnology 2, no. 3 (September 2017): 192–97. http://dx.doi.org/10.1016/j.synbio.2017.09.001.

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Chen, Guo-Qiang, Xin-Yu Chen, Fu-Qing Wu, and Jin-Chun Chen. "Polyhydroxyalkanoates (PHA) toward cost competitiveness and functionality." Advanced Industrial and Engineering Polymer Research 3, no. 1 (January 2020): 1–7. http://dx.doi.org/10.1016/j.aiepr.2019.11.001.

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Rogala, Małgorzata Marta, Jan Gawor, Robert Gromadka, Magdalena Kowalczyk, and Jakub Grzesiak. "Biodiversity and Habitats of Polar Region Polyhydroxyalkanoic Acid-Producing Bacteria: Bioprospection by Popular Screening Methods." Genes 11, no. 8 (July 31, 2020): 873. http://dx.doi.org/10.3390/genes11080873.

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Polyhydroxyalkanoates (PHAs), the intracellular polymers produced by various microorganisms as carbon and energy storage, are of great technological potential as biodegradable versions of common plastics. PHA-producing microbes are therefore in great demand and a plethora of different environments, especially extreme habitats, have been probed for the presence of PHA-accumulators. However, the polar region has been neglected in this regard, probably due to the low accessibility of the sampling material and unusual cultivation regime. Here, we present the results of a screening procedure involving 200 bacterial strains isolated from 25 habitats of both polar regions. Agar-based tests, microscopy, and genetic methods were conducted to elucidate the biodiversity and potential of polar-region PHA-accumulators. Microscopic observation of Nile Red stained cells proved to be the most reliable screening method as it allowed to confirm the characteristic bright orange glow of the Nile Red–PHA complex as well as the typical morphology of the PHA inclusions. Psychrophilic PHA-producers belonged mostly to the Comamonadaceae family (Betaproteobacteria) although actinobacterial PHA synthesizers of the families, Microbacteriaceae and Micrococcaceae also featured prominently. Glacial and postglacial habitats as well as developed polar region soils, were evaluated as promising for PHA-producer bioprospection. This study highlights the importance of psychrophiles as biodiverse and potent polyhydroxyalkanoate sources for scientific and application-aimed research.

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Fernandez-Bunster, Guillermo, and Pamela Pavez. "Novel Production Methods of Polyhydroxyalkanoates and Their Innovative Uses in Biomedicine and Industry." Molecules 27, no. 23 (November 30, 2022): 8351. http://dx.doi.org/10.3390/molecules27238351.

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Polyhydroxyalkanoate (PHA), a biodegradable polymer obtained from microorganisms and plants, have been widely used in biomedical applications and devices, such as sutures, cardiac valves, bone scaffold, and drug delivery of compounds with pharmaceutical interests, as well as in food packaging. This review focuses on the use of polyhydroxyalkanoates beyond the most common uses, aiming to inform about the potential uses of the biopolymer as a biosensor, cosmetics, drug delivery, flame retardancy, and electrospinning, among other interesting uses. The novel applications are based on the production and composition of the polymer, which can be modified by genetic engineering, a semi-synthetic approach, by changing feeding carbon sources and/or supplement addition, among others. The future of PHA is promising, and despite its production costs being higher than petroleum-based plastics, tools given by synthetic biology, bioinformatics, and machine learning, among others, have allowed for great production yields, monomer and polymer functionalization, stability, and versatility, a key feature to increase the uses of this interesting family of polymers.

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Ben Abdallah, Manel, Fatma Karray, and Sami Sayadi. "Production of Polyhydroxyalkanoates by Two Halophilic Archaeal Isolates from Chott El Jerid Using Inexpensive Carbon Sources." Biomolecules 10, no. 1 (January 8, 2020): 109. http://dx.doi.org/10.3390/biom10010109.

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The large use of conventional plastics has resulted in serious environmental problems. Polyhydroxyalkanoates represent a potent replacement to synthetic plastics because of their biodegradable nature. This study aimed to screen bacteria and archaea isolated from an extreme environment, the salt lake Chott El Jerid for the accumulation of these inclusions. Among them, two archaeal strains showed positive results with phenotypic and genotypic methods. Phylogenetic analysis, based on the 16S rRNA gene, indicated that polyhydroxyalkanoate (PHA)-producing archaeal isolates CEJGTEA101 and CEJEA36 were related to Natrinema altunense and Haloterrigena jeotgali, respectively. Gas chromatography and UV-visible spectrophotometric analyses revealed that the PHA were identified as polyhydroxybutyrate and polyhydroxyvalerate, respectively. According to gas chromatography analysis, the strain CEJGTEA101 produced maximum yield of 7 wt % at 37 °C; pH 6.5; 20% NaCl and the strain CEJEA36 produced 3.6 wt % at 37 °C; pH 7; 25% NaCl in a medium supplemented with 2% glucose. Under nutritionally optimal cultivation conditions, polymers were extracted from these strains and were determined by gravimetric analysis yielding PHA production of 35% and 25% of cell dry weight. In conclusion, optimization of PHA production from inexpensive industrial wastes and carbon sources has considerable interest for reducing costs and obtaining high yield.

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Martínez, Virginia, Fernando de la Peña, Javier García-Hidalgo, Isabel de la Mata, José Luis García, and María Auxiliadora Prieto. "Identification and Biochemical Evidence of a Medium-Chain-Length Polyhydroxyalkanoate Depolymerase in the Bdellovibrio bacteriovorus Predatory Hydrolytic Arsenal." Applied and Environmental Microbiology 78, no. 17 (June 15, 2012): 6017–26. http://dx.doi.org/10.1128/aem.01099-12.

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ABSTRACTThe obligate predatorBdellovibrio bacteriovorusHD100 shows a large set of proteases and other hydrolases as part of its hydrolytic arsenal needed for its predatory life cycle. We present genetic and biochemical evidence that open reading frame (ORF) Bd3709 ofB. bacteriovorusHD100 encodes a novel medium-chain-length polyhydroxyalkanoate (mcl-PHA) depolymerase (PhaZBd). The primary structure of PhaZBdsuggests that this enzyme belongs to the α/β-hydrolase fold family and has a typical serine hydrolase catalytic triad (serine-histidine-aspartic acid) in agreement with other PHA depolymerases and lipases. PhaZBdhas been extracellularly produced using different hypersecretor Tol-pal mutants ofEscherichia coliandPseudomonas putidaas recombinant hosts. The recombinant PhaZBdhas been characterized, and its biochemical properties have been compared to those of other PHA depolymerases. The enzyme behaves as a serine hydrolase that is inhibited by phenylmethylsulfonyl fluoride. It is also affected by the reducing agent dithiothreitol and nonionic detergents like Tween 80. PhaZBdis an endoexohydrolase that cleaves both large and small PHA molecules, producing mainly dimers but also monomers and trimers. The enzyme specifically degrades mcl-PHA and is inactive toward short-chain-length polyhydroxyalkanoates (scl-PHA) like polyhydroxybutyrate (PHB). These studies shed light on the potentiality of these predators as sources of new biocatalysts, such as an mcl-PHA depolymerase, for the production of enantiopure hydroxyalkanoic acids and oligomers as building blocks for the synthesis of biobased polymers.

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Rodrigues, Ana Marta, Rita Dias Guardão Franca, Madalena Dionísio, Chantal Sevrin, Christian Grandfils, Maria A. M. Reis, and Nídia Dana Lourenço. "Polyhydroxyalkanoates from a Mixed Microbial Culture: Extraction Optimization and Polymer Characterization." Polymers 14, no. 11 (May 25, 2022): 2155. http://dx.doi.org/10.3390/polym14112155.

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Polyhydroxyalkanoates (PHA) are biopolymers with potential to replace conventional oil-based plastics. However, PHA high production costs limit their scope of commercial applications. Downstream processing is currently the major cost factor for PHA production but one of the least investigated aspects of the PHA production chain. In this study, the extraction of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) produced at pilot scale by a mixed microbial culture was performed using sodium hydroxide (NaOH) or sodium hypochlorite (NaClO) as digestion agents of non-PHA cellular mass. Optimal conditions for digestion with NaOH (0.3 M, 4.8 h) and NaClO (9.0%, 3.4 h) resulted in polymers with a PHA purity and recovery of ca. 100%, in the case of the former and ca. 99% and 90%, respectively, in the case of the latter. These methods presented higher PHA recoveries than extraction by soxhlet with chloroform, the benchmark protocol for PHA extraction. The polymers extracted by the three methods presented similar PHA purities, molecular weights and polydispersity indices. Using the optimized conditions for NaOH and NaClO digestions, this study analyzed the effect of the initial intracellular PHA content (40–70%), biomass concentration (20–100 g/L) and biomass pre-treatment (fresh vs. dried vs. lyophilized) on the performance of PHA extraction by these two methods.

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Wang, Ke, Chang Chen, and Ruihong Zhang. "Process Development of Polyhydroxyalkanoates Production by Halophiles Valorising Food Waste." Bioengineering 9, no. 11 (November 1, 2022): 630. http://dx.doi.org/10.3390/bioengineering9110630.

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Polyhydroxyalkanoates (PHA) is an emerging biodegradable plastic family that can replace a broad spectrum of conventional thermoplastics and is promising in the sustainable process development and valorization of organic waste. This study established a novel production system of PHA from food waste through halophilic microbial fermentation with spent medium recycling. The essential processing parameters for batch cultivation of Haloferax mediterranei were optimized for food waste substrate (a 40 g/L loading and 2.5 vvm of aeration), which achieved a yield of 0.3 g PHA/g COD consumed. A batch bioreactor system was developed, which produced 7.0 ± 0.7 g/L cell dry mass and 4.5 ± 0.2 g/L PHA with a 20% dissolved oxygen (DO) level. A DO above 50% saturation resulted in faster cell growth and similar cell mass production but 25% less PHA production. The spent saline medium, treated with H2O2 and rotary evaporation, was successfully reused for four consecutive batches and provided consistent PHA concentrations and product qualities.

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Hall, Brian, Jennifer Baldwin, Ho Gun Rhie, and Douglas Dennis. "Cloning of the Nocardia corallina polyhydroxyalkanoate synthase gene and production of poly-(3-hydroxybutyrate-co-3-hydroxyhexanoate) and poly-(3-hydroxyvalerate-co-3-hydroxyheptanoate)." Canadian Journal of Microbiology 44, no. 7 (July 1, 1998): 687–91. http://dx.doi.org/10.1139/w98-048.

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The polyhydroxyalkanoate (PHA) synthase gene (phaCNc) from Nocardia corallina was identified in a lambda library on a 6-kb BamHI fragment. A 2.8-kb XhoII subfragment was found to contain the ntact PHA synthase. This 2.8-kb fragment was subjected to DNA sequencing and was found to contain the coding region for the PHA synthase and a small downstream open reading frame of unknown function. On the basis of DNA sequence, phaCNc is closest in homology to the PHA synthases (phaCPaI and phaCPaII) of Pseudomonas aeruginosa (approximately 41% identity and 55% similarity). The 2.8-kb XhoII fragment containing phaCNc was subcloned into broad host range mobilizable plasmids and transferred into Escherichia coli, Klebsiella aerogenes (both containing a plasmid bearing phaA and phaB from Ralstonia eutropha), and PHA-negative strains of R. eutropha and Pseudomonas putida. The recombinant strains were grown on various carbon sources and the resulting polymers were analyzed. In these strains, the PHA synthase from N. corallina was able to mediate the production of poly(3-hydroxybutyrate-co-3-hydroxy-hexanoate) containing high levels of 3-hydroxyhexanoate when grown on hexanoate and larger even-chain fatty acids and poly(3-hydroxyvalerate-co-3-hydroxyheptanoate) containing high levels of 3-hydroxyheptanoate when grown on heptanoate or larger odd-chain fatty acids. Key words: polyhydroxyalkanoates (PHAs), Nocardia corallina, biodegradable, polyester.

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Szacherska, Karolina, Piotr Oleskowicz-Popiel, Slawomir Ciesielski, and Justyna Mozejko-Ciesielska. "Volatile Fatty Acids as Carbon Sources for Polyhydroxyalkanoates Production." Polymers 13, no. 3 (January 20, 2021): 321. http://dx.doi.org/10.3390/polym13030321.

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Waste of industrial origin produced from synthetic materials are a serious threat to the natural environment. The ending resources of fossil raw materials and increasingly restrictive legal standards for the management of plastic waste have led to research on the use of biopolymers, which, due to their properties, may be an ecological alternative to currently used petrochemical polymers. Polyhydroxyalkanoates (PHAs) have gained much attention in recent years as the next generation of environmentally friendly materials. Currently, a lot of research is being done to reduce the costs of the biological process of PHA synthesis, which is the main factor limiting the production of PHAs on the industrial scale. The volatile fatty acids (VFAs) produced by anaerobic digestion from organic industrial and food waste, and various types of wastewater could be suitable carbon sources for PHA production. Thus, reusing the organic waste, while reducing the future fossil fuel, originated from plastic waste. PHA production from VFAs seem to be a good approach since VFAs composition determines the constituents of PHAs polymer and is of great influence on its properties. In order to reduce the overall costs of PHA production to a more reasonable level, it will be necessary to design a bioprocess that maximizes VFAs production, which will be beneficial for the PHA synthesis. Additionally, a very important factor that affects the profitable production of PHAs from VFAs is the selection of a microbial producer that will effectively synthesize the desired bioproduct. PHA production from VFAs has gained significant interest since VFAs composition determines the constituents of PHA polymer. Thus far, the conversion of VFAs into PHAs using pure bacterial cultures has received little attention, and the majority of studies have used mixed microbial communities for this purpose. This review discusses the current state of knowledge on PHAs synthesized by microorganisms cultured on VFAs.

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Itzigsohn, Robin, Oded Yarden, and Yaacov Okon. "Polyhydroxyalkanoate analysis inAzospirillum brasilense." Canadian Journal of Microbiology 41, no. 13 (December 15, 1995): 73–76. http://dx.doi.org/10.1139/m95-171.

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The considerable industrial interest in the qualitative and quantitative production of polyhydroxyalkanoates in microorganisms has led to the characterization of those synthesized in the nitrogen-fixing bacteria Azospirillum brasilense and Azotobacter paspali. In contrast to some other bacterial species, Azospirillum brasilense does not produce copolymers of hydroxyalkanoates when grown under the different carbon sources assayed, namely n-alkanoic acids, hydroxyalkanoates, and sugars with varying C:N ratios. Rather, only homopolymers of polyhydroxybutyrate were detected, comprising up to 70% of the cell dry mass. No copolymers were detected in Azotobacter paspali. Quantitative analyses of poly(β-hydroxybutyrate) are also presented.Key words: Azospirillum spp., Azotobacter paspali, polyhydroxyalkanoate analysis, PHA, PHB.

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Carvalho, João M., Bruno C. Marreiros, and Maria A. M. Reis. "Polyhydroxyalkanoates Production by Mixed Microbial Culture under High Salinity." Sustainability 14, no. 3 (January 25, 2022): 1346. http://dx.doi.org/10.3390/su14031346.

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The fishing industry produces vast amounts of saline organic side streams that require adequate treatment and disposal. The bioconversion of saline resources into value-added products, such as biodegradable polyhydroxyalkanoates (PHAs), has not yet been fully explored. This study investigated PHA production by mixed microbial cultures under 30 gNaCl/L, the highest NaCl concentration reported for the acclimatization of a PHA-accumulating mixed microbial culture (MMC). The operational conditions used during the culture-selection stage resulted in an enriched PHA-accumulating culture dominated by the Rhodobacteraceae family (95.2%) and capable of storing PHAs up to 84.1% wt. (volatile suspended solids (VSS) basis) for the highest organic loading rate (OLR) applied (120 Cmmol/(L.d)). This culture presented a higher preference for the consumption of valeric acid (0.23 ± 0.03 CmolHVal/(CmolX.h)), and the 3HV monomer polymerization (0.33 ± 0.04 CmmolHV/(CmmolX.h) was higher as well. As result, a P(3HB-co-3HV)) with high HV content (63% wt.) was produced in the accumulation tests conducted at higher OLRs and with 30 gNaCl/L. A global volumetric PHA productivity of 0.77 gPHA/(L.h) and a specific PHA productivity of 0.21 gPHA/(gX.h) were achieved. These results suggested the significant potential of the bioconversion of saline resources into value-added products, such as PHAs.

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Yao, Hui, Daixu Wei, Xuemei Che, Longwei Cai, Lei Tao, Lei Liu, Linping Wu, and Guo-Qiang Chen. "Comb-like temperature-responsive polyhydroxyalkanoate-graft-poly(2-dimethylamino-ethylmethacrylate) for controllable protein adsorption." Polymer Chemistry 7, no. 38 (2016): 5957–65. http://dx.doi.org/10.1039/c6py01235c.

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Albuquerque, Priscilla Barbosa Sales de, Katarynna Santos de Araújo, Kelvin Augusto Azevedo da Silva, Laureen Michelle Houllou, Gabriel Olivo Locatelli, and Carolina Barbosa Malafaia. "Potential production of bioplastics polyhydroxyalkanoates using residual glycerol." Journal of Environmental Analysis and Progress 3, no. 1 (January 22, 2018): 055–60. http://dx.doi.org/10.24221/jeap.3.1.2018.1701.055-060.

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Cupriavidus necator was used for polyhydroxyalkanoate (PHA) production with the aim to compare the substrate consumption between pure glycerol (PG) and the glycerol obtained from biodiesel industry (GB). Shake flask experiments were performed with 20 g/L for both the carbon sources, incubated in a shaking incubator at 35 ºC for up to 72 h. At the end, the residual carbon source was analyzed by HPLC, the biomass recuperation for biopolymer extraction and biopolymer characterized by FTIR. The results demonstrated that 35.75 % of PG was consumed during biomass production, while 45.08 % was the value consumed for GB, which can indicate the higher PHA accumulation in GB-sample, as observed by microscopy analyses. Fourier Transform Infrared (FTIR) spectroscopy was performed to confirm the PHA nature of PG and GB samples, and confirmed the establishment of more hydrogen bonds in the PG one, suggesting the surplus of glycerol in the obtained-biopolymer. Since it is interesting the utilization of GB for obtaining added-value products along with biodiesel, this study reported the efficient production of PHA by C. necator using GB as carbon source and its promising use in the bioplastic industry as an alternative product for petrochemical plastics, foreseeing the improvement of a sustainable industry based on biofuels and biopolymers.

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Zhang, Bo, Ross Carlson, and Friedrich Srienc. "Engineering the Monomer Composition of Polyhydroxyalkanoates Synthesized in Saccharomyces cerevisiae." Applied and Environmental Microbiology 72, no. 1 (January 2006): 536–43. http://dx.doi.org/10.1128/aem.72.1.536-543.2006.

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ABSTRACT Polyhydroxyalkanoates (PHAs) have received considerable interest as renewable-resource-based, biodegradable, and biocompatible plastics with a wide range of potential applications. We have engineered the synthesis of PHA polymers composed of monomers ranging from 4 to 14 carbon atoms in either the cytosol or the peroxisome of Saccharomyces cerevisiae by harnessing intermediates of fatty acid metabolism. Cytosolic PHA production was supported by establishing in the cytosol critical β-oxidation chemistries which are found natively in peroxisomes. This platform was utilized to supply medium-chain (C6 to C14) PHA precursors from both fatty acid degradation and synthesis to a cytosolically expressed medium-chain-length (mcl) polymerase from Pseudomonas oleovorans. Synthesis of short-chain-length PHAs (scl-PHAs) was established in the peroxisome of a wild-type yeast strain by targeting the Ralstonia eutropha scl polymerase to the peroxisome. This strain, harboring a peroxisomally targeted scl-PHA synthase, accumulated PHA up to approximately 7% of its cell dry weight. These results indicate (i) that S. cerevisiae expressing a cytosolic mcl-PHA polymerase or a peroxisomal scl-PHA synthase can use the 3-hydroxyacyl coenzyme A intermediates from fatty acid metabolism to synthesize PHAs and (ii) that fatty acid degradation is also possible in the cytosol as β-oxidation might not be confined only to the peroxisomes. Polymers of even-numbered, odd-numbered, or a combination of even- and odd-numbered monomers can be controlled by feeding the appropriate substrates. This ability should permit the rational design and synthesis of polymers with desired material properties.

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Sudesh, Kumar, Toshiaki Fukui, Tadahisa Iwata, and Yoshiharu Doi. "Factors affecting the freeze-fracture morphology of in vivo polyhydroxyalkanoate granules." Canadian Journal of Microbiology 46, no. 4 (April 1, 2000): 304–11. http://dx.doi.org/10.1139/w99-150.

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Interesting morphologies were observed when Comamonas acidovorans containing polyhydroxyalkanoates (PHA) of various compositions was freeze-fractured at temperatures far below the glass transition temperatures of PHA. In vivo granules of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) comparatively showed the most ductility, and could be stretched extensively. Contrary to the uniform needle-type deformation shown by the poly(3-hydroxybutyrate) homopolymer when fractured at -110°C, copolymers containing 3-hydroxyvalerate units showed various deformation structures. Similar observations were made when in vivo granules of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) were freeze-fractured, although the ductility of the latter was much reduced. In addition, it was found that fracturing at -160°C resulted in decreased ductility of the PHA granules with the concomitant increase in the number of mushroom-type deformation structures. Our results suggest that PHA granules with higher resistance to freeze-fracture deformation show less ductility, and therefore produce the mushroom-type morphology. This is the first report on the freeze-fracture morphology of PHA copolymers containing short-chain-length monomers.Key words: polyhydroxyalkanoates, freeze-fracture electron microscopy, poly(4-hydroxybutyrate), Comamonas acidovorans, biodegradable plastic.

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Munir, S., and N. Jamil. "Characterization of Polyhydroxyalkanoates Produced by Contaminated Soil Bacteria using Wastewater and Glucose as Carbon Sources." Tropical Journal of Pharmaceutical Research 14, no. 9 (October 9, 2015): 1605–11. http://dx.doi.org/10.4314/tjpr.v14i9.9.

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Purpose: To isolate polyhydroxyalkanoates (PHA)-producing bacterial strains from contaminated soil using industrial wastewater and glucose as carbon soured by Macrogen sequencing. Two different sources, namely, glucose and wastewater were used to ces.Methods: The strains were isolated and identified as Pseudomonas, Bacillus, Enterobacter, Exiguobacterium and Stenotrophomonas using biochemical tests and further confirmevaluate and compare the use of wastewater as a carbon source for PHA production. The biomass obtained was analyzed by Fourier transform infra-red (FTIR) to identify the presence of PHA in it. Afterwards, PHA extraction was carried out and then gas chromatography (GC) performed to identify PHA monomers.Results: Utilization of glucose resulted in the production of PHB, while wastewater yielded copolymers poly-3 hydroxybutyrate-co-3hydroxyvalerate P(3HB-co-3HV) due to its content of volatile fatty acids such as acetic acid, propionic acid and butyric acid, which led to the production of different types of polymers. The maximum PHA production was 41 ± 0.22 % obtained for Stenotrophomonas (SM03) using 2 % glucose as carbon source while for wastewater, maximum production was achieved by the Pseudomonas strain (SM01).Conclusion: Wastewater is produced in large quantities daily during various activities and therefore can be used as a cheap carbon source for the production of valuable products such as PHA.Keywords: Polyhydroxyalkanoates, Wastewater, Glucose, Pseudomonas strain, Stenotrophomonas

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Bengtsson, Simon, Alan Werker, and Thomas Welander. "Production of polyhydroxyalkanoates by glycogen accumulating organisms treating a paper mill wastewater." Water Science and Technology 58, no. 2 (August 1, 2008): 323–30. http://dx.doi.org/10.2166/wst.2008.381.

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A process for production of polyhydroxyalkanoates (PHA) by activated sludge treating a paper mill wastewater was investigated. The applied strategy was to select for glycogen accumulating organisms (GAOs) by alternating anaerobic/aerobic conditions. Acidogenic fermentation was used as pretreatment to convert various organic compounds to volatile fatty acids which are preferable substrates for PHA production. Enrichment resulted in a culture dominated by GAOs related to Defluviicoccus vanus (56%) and Candidatus Competibacter phosphatis (22%). Optimization of PHA accumulation by the enriched GAO culture was performed through batch experiments. Accumulation of PHA under anaerobic conditions was limited by the intracellular glycogen stored. Under aerobic conditions significant glycogen production (to 25% of sludge dry weight) was observed alongside PHA accumulation (to 22% of sludge dry weight). By applying a subsequent anaerobic period after an initial aerobic, the produced glycogen could be utilized for further PHA accumulation and by this strategy PHA content was increased to 42% of sludge dry weight. The PHA yield over the entire process was 0.10 kg per kg of influent COD treated which is similar to what has been achieved with a process applying feast/famine enrichment strategy with the same wastewater.

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Ishii-Hyakutake, Manami, Shoji Mizuno, and Takeharu Tsuge. "Biosynthesis and Characteristics of Aromatic Polyhydroxyalkanoates." Polymers 10, no. 11 (November 14, 2018): 1267. http://dx.doi.org/10.3390/polym10111267.

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Polyhydroxyalkanoates (PHAs) are polyesters synthesized by bacteria as a carbon and energy storage material. PHAs are characterized by thermoplasticity, biodegradability, and biocompatibility, and thus have attracted considerable attention for use in medical, agricultural, and marine applications. The properties of PHAs depend on the monomer composition and many types of PHA monomers have been reported. This review focuses on biosynthesized PHAs bearing aromatic groups as side chains. Aromatic PHAs show characteristics different from those of aliphatic PHAs. This review summarizes the types of aromatic PHAs and their characteristics, including their thermal and mechanical properties and degradation behavior. Furthermore, the effect of the introduction of an aromatic monomer on the glass transition temperature (Tg) of PHAs is discussed. The introduction of aromatic monomers into PHA chains is a promising method for improving the properties of PHAs, as the characteristics of aromatic PHAs differ from those of aliphatic PHAs.

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Ren, Lian Hai, Hui Liu, and Pan Wang. "Synthesis of Polyhydroxyalkanoates from Waste Frying Oil by Cupriavidus necator." Applied Mechanics and Materials 768 (June 2015): 124–31. http://dx.doi.org/10.4028/www.scientific.net/amm.768.124.

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Waste frying oil is abundant and can be used as a cheaper carbon source in PHA production. The utilization of waste frying oil for production of PHA not only enhances the economics of such products,but also provides with a strategy to overcome disposal problems. In this study, the waste frying oil is used as the carbon source for the synthesis of PHA by Cupriavidus necator (formerly known as Ralstonia eutropha) to find out the best growth conditions in order to provides the basis for producing PHA in industry. The results showed that the optimal conditions for production of PHA was at the temperature of 25°C, pH 7, C/N ratio (w/w) 20:0.75 and incubation time 72h. The maximum concentration of PHA was obtained as 7.04g/L.

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Vigneswari, Sevakumaran, Muhammad Shahrul Md Noor, Tan Suet May Amelia, Karthnee Balakrishnan, Azila Adnan, Kesaven Bhubalan, Al-Ashraf Abdullah Amirul, and Seeram Ramakrishna. "Recent Advances in the Biosynthesis of Polyhydroxyalkanoates from Lignocellulosic Feedstocks." Life 11, no. 8 (August 10, 2021): 807. http://dx.doi.org/10.3390/life11080807.

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Polyhydroxyalkanoates (PHA) are biodegradable polymers that are considered able to replace synthetic plastic because their biochemical characteristics are in some cases the same as other biodegradable polymers. However, due to the disadvantages of costly and non-renewable carbon sources, the production of PHA has been lower in the industrial sector against conventional plastics. At the same time, first-generation sugar-based cultivated feedstocks as substrates for PHA production threatens food security and considerably require other resources such as land and energy. Therefore, attempts have been made in pursuit of suitable sustainable and affordable sources of carbon to reduce production costs. Thus, in this review, we highlight utilising waste lignocellulosic feedstocks (LF) as a renewable and inexpensive carbon source to produce PHA. These waste feedstocks, second-generation plant lignocellulosic biomass, such as maize stoves, dedicated energy crops, rice straws, wood chips, are commonly available renewable biomass sources with a steady supply of about 150 billion tonnes per year of global yield. The generation of PHA from lignocellulose is still in its infancy, hence more screening of lignocellulosic materials and improvements in downstream processing and substrate pre-treatment are needed in the future to further advance the biopolymer sector.

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bin Bakri, Muhammad Khusairy, Elammaran Jayamani, and Akshay Kakar. "Potential in the Development of Borneo Acacia Wood Reinforced Polyhydroxyalkanoates Bio-Composites." Key Engineering Materials 779 (September 2018): 19–24. http://dx.doi.org/10.4028/www.scientific.net/kem.779.19.

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This research focuses on the mechanical and morphological properties of acacia wood (AW) reinforced polyhydroxyalkanoates (PHA) bio-composites. Acacia woods waste in the form of sawdust was processed into short wood fiber, which was later mixed with pure PHA with different fiber loading (5wt%, 10wt%, 15wt% and 20wt%). The acacia wood fibers were chemically modified by using the naturalization technique (which used both acidic and alkaline base) using acetic acid and sodium bicarbonate. The hot press machine was used to fabricate the samples. Tensile and flexural samples were fabricated and tested according to the ASTM standards. The SEM images show that the chemically modified acacia wood reinforced PHA (M-AW-PHA) bio-composites create desirable adhesion which contributed to better mechanical strength at 15wt%, when compared with untreated acacia wood reinforced PHA (U-AW-PHA) bio-composites.

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Nagarajan, Dillirani, Ganies Riza Aristya, Yu-Ju Lin, Jui-Jen Chang, Hong-Wei Yen, and Jo-Shu Chang. "Microbial cell factories for the production of polyhydroxyalkanoates." Essays in Biochemistry 65, no. 2 (July 2021): 337–53. http://dx.doi.org/10.1042/ebc20200142.

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Abstract Pollution caused by persistent petro-plastics is the most pressing problem currently, with 8 million tons of plastic waste dumped annually in the oceans. Plastic waste management is not systematized in many countries, because it is laborious and expensive with secondary pollution hazards. Bioplastics, synthesized by microorganisms, are viable alternatives to petrochemical-based thermoplastics due to their biodegradable nature. Polyhydroxyalkanoates (PHAs) are a structurally and functionally diverse group of storage polymers synthesized by many microorganisms, including bacteria and Archaea. Some of the most important PHA accumulating bacteria include Cupriavidus necator, Burkholderia sacchari, Pseudomonas sp., Bacillus sp., recombinant Escherichia coli, and certain halophilic extremophiles. PHAs are synthesized by specialized PHA polymerases with assorted monomers derived from the cellular metabolite pool. In the natural cycle of cellular growth, PHAs are depolymerized by the native host for carbon and energy. The presence of these microbial PHA depolymerases in natural niches is responsible for the degradation of bioplastics. Polyhydroxybutyrate (PHB) is the most common PHA with desirable thermoplastic-like properties. PHAs have widespread applications in various industries including biomedicine, fine chemicals production, drug delivery, packaging, and agriculture. This review provides the updated knowledge on the metabolic pathways for PHAs synthesis in bacteria, and the major microbial hosts for PHAs production. Yeasts are presented as a potential candidate for industrial PHAs production, with their high amenability to genetic engineering and the availability of industrial-scale technology. The major bottlenecks in the commercialization of PHAs as an alternative for plastics and future perspectives are also critically discussed.

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Carvalheira, Mónica, Catarina L. Amorim, Ana Catarina Oliveira, Eliana C. Guarda, Eunice Costa, Margarida Ribau Teixeira, Paula M. L. Castro, Anouk F. Duque, and Maria A. M. Reis. "Valorization of Brewery Waste through Polyhydroxyalkanoates Production Supported by a Metabolic Specialized Microbiome." Life 12, no. 9 (August 30, 2022): 1347. http://dx.doi.org/10.3390/life12091347.

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Raw brewers’ spent grain (BSG), a by-product of beer production and produced at a large scale, presents a composition that has been shown to have potential as feedstock for several biological processes, such as polyhydroxyalkanoates (PHAs) production. Although the high interest in the PHA production from waste, the bioconversion of BSG into PHA using microbial mixed cultures (MMC) has not yet been explored. This study explored the feasibility to produce PHA from BSG through the enrichment of a mixed microbial culture in PHA-storing organisms. The increase in organic loading rate (OLR) was shown to have only a slight influence on the process performance, although a high selectivity in PHA-storing microorganisms accumulation was reached. The culture was enriched on various PHA-storing microorganisms, such as bacteria belonging to the Meganema, Carnobacterium, Leucobacter, and Paracocccus genera. The enrichment process led to specialization of the microbiome, but the high diversity in PHA-storing microorganisms could have contributed to the process stability and efficiency, allowing for achieving a maximum PHA content of 35.2 ± 5.5 wt.% (VSS basis) and a yield of 0.61 ± 0.09 CmmolPHA/CmmolVFA in the accumulation assays. Overall, the production of PHA from fermented BSG is a feasible process confirming the valorization potential of the feedstock through the production of added-value products.

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Khomlaem, Chanin, Hajer Aloui, and Beom Soo Kim. "Biosynthesis of Polyhydroxyalkanoates from Defatted Chlorella Biomass as an Inexpensive Substrate." Applied Sciences 11, no. 3 (January 25, 2021): 1094. http://dx.doi.org/10.3390/app11031094.

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Microalgae biomass has been recently used as an inexpensive substrate for the industrial production of polyhydroxyalkanoates (PHAs). In this work, a dilute acid pretreatment using 0.3 N of hydrochloric acid (HCl) was performed to extract reducing sugars from 10% (w/v) of defatted Chlorella biomass (DCB). The resulting HCl DCB hydrolysate was used as a renewable substrate to assess the ability of three bacterial strains, namely Bacillus megaterium ALA2, Cupriavidus necator KCTC 2649, and Haloferax mediterranei DSM 1411, to produce PHA in shake flasks. The results show that under 20 g/L of DCB hydrolysate derived sugar supplementation, the cultivated strains successfully accumulated PHA up to 29.7–75.4% of their dry cell weight (DCW). Among the cultivated strains, C. necator KCTC 2649 exhibited the highest PHA production (7.51 ± 0.20 g/L, 75.4% of DCW) followed by H. mediterranei DSM 1411 and B. megaterium ALA2, for which a PHA content of 3.79 ± 0.03 g/L (55.5% of DCW) and 0.84 ± 0.06 g/L (29.7% of DCW) was recorded, respectively. Along with PHA, a maximum carotenoid content of 1.80 ± 0.16 mg/L was produced by H. mediterranei DSM 1411 at 120 h of cultivation in shake flasks. PHA and carotenoid production increased by 1.45- and 1.37-fold, respectively, when HCl DCB hydrolysate biotransformation was upscaled to a 1 L of working volume fermenter. Based on FTIR and 1H NMR analysis, PHA polymers accumulated by B. megaterium ALA2 and C. necator KCTC 2649 were identified as homopolymers of poly(3-hydroxybutyrate). However, a copolymer of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) with a 3-hydroxyvalerate fraction of 10.5 mol% was accumulated by H. mediterranei DSM 1411.

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Singh Saharan, Baljeet, Anita Grewal, and Pardeep Kumar. "Biotechnological Production of Polyhydroxyalkanoates: A Review on Trends and Latest Developments." Chinese Journal of Biology 2014 (February 24, 2014): 1–18. http://dx.doi.org/10.1155/2014/802984.

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Polyhydroxyalkanoates (PHA) producers have been reported to reside at various ecological niches which are naturally or accidently exposed to high organic matter or growth limited conditions such as dairy wastes, hydrocarbon contaminated sites, pulp and paper mill wastes, agricultural wastes, activated sludges of treatment plants, rhizosphere, and industrial effluents. Few among them also produce extracellular by-products like rhamnolipids, extracellular polymeric substances, and biohydrogen gas. These sorts of microbes are industrially important candidates for the reason that they can use waste materials of different origin as substrate with simultaneous production of valuable bioproducts including PHA. Implementation of integrated system to separate their by-products (intracellular and extracellular) can be economical in regard to production. In this review, we have discussed various microorganisms dwelling at different environmental conditions which stimulate them to accumulate carbon as polyhydroxyalkanoates granules and factors influencing its production and composition. A brief aspect on metabolites which are produced concomitantly with PHA has also been discussed. In conclusion, exploring of capabilities like of dual production by microbes and use of wastes as renewable substrate under optimized cultural conditions either in batch or continuous process can cause deduction in present cost of bioplastic production from stored PHA granules.

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Kouřilová, Xenie, Jana Schwarzerová, Iva Pernicová, Karel Sedlář, Kateřina Mrázová, Vladislav Krzyžánek, Jana Nebesářová, and Stanislav Obruča. "The First Insight into Polyhydroxyalkanoates Accumulation in Multi-Extremophilic Rubrobacter xylanophilus and Rubrobacter spartanus." Microorganisms 9, no. 5 (April 24, 2021): 909. http://dx.doi.org/10.3390/microorganisms9050909.

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Actinobacteria belonging to the genus Rubrobacter are known for their multi-extremophilic growth conditions—they are highly radiation-resistant, halotolerant, thermotolerant or even thermophilic. This work demonstrates that the members of the genus are capable of accumulating polyhydroxyalkanoates (PHA) since PHA-related genes are widely distributed among Rubrobacter spp. whose complete genome sequences are available in public databases. Interestingly, all Rubrobacter strains possess both class I and class III synthases (PhaC). We have experimentally investigated the PHA accumulation in two thermophilic species, R. xylanophilus and R. spartanus. The PHA content in both strains reached up to 50% of the cell dry mass, both bacteria were able to accumulate PHA consisting of 3-hydroxybutyrate and 3-hydroxyvalerate monomeric units, none other monomers were incorporated into the polymer chain. The capability of PHA accumulation likely contributes to the multi-extremophilic characteristics since it is known that PHA substantially enhances the stress robustness of bacteria. Hence, PHA can be considered as extremolytes enabling adaptation to extreme conditions. Furthermore, due to the high PHA content in biomass, a wide range of utilizable substrates, Gram-stain positivity, and thermophilic features, the Rubrobacter species, in particular Rubrobacter xylanophilus, could be also interesting candidates for industrial production of PHA within the concept of Next-Generation Industrial Biotechnology.

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Vigneswari, S., J. M. Chai, K. Shantini, K. Bhubalan, and A. A. Amirul. "Designing Novel Interfaces via Surface Functionalization of Short-Chain-Length Polyhydroxyalkanoates." Advances in Polymer Technology 2019 (March 3, 2019): 1–15. http://dx.doi.org/10.1155/2019/3831251.

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Polyhydroxyalkanoates (PHA), a microbial plastic has emerged as promising biomaterial owing to the broad range of mechanical properties. However, some studies revealed that PHA is hydrophobic and has no recognition site for cell attachment and this is often a limitation in tissue engineering aspects. Owing to this, the polymer is tailored accordingly in order to enhance the biocompatibilityin vivoas well as to suit the intended application. Thus far, these surface modifications have led to PHA being widely used in various biomedical and pharmaceutical applications such as cardiac patches, wound management, nerve, bone, and cartilage repair. This review addresses the surface modification on biomedical applications focusing on short-chain-length PHA such as poly(3-hydroxybutyrate) [P(3HB)], poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [P(3HB-co-4HB)] and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)].

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Javaid, Hadiqa, Ali Nawaz, Naveeda Riaz, Hamid Mukhtar, Ikram -Ul-Haq, Kanita Ahmed Shah, Hooria Khan, et al. "Biosynthesis of Polyhydroxyalkanoates (PHAs) by the Valorization of Biomass and Synthetic Waste." Molecules 25, no. 23 (November 26, 2020): 5539. http://dx.doi.org/10.3390/molecules25235539.

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Synthetic pollutants are a looming threat to the entire ecosystem, including wildlife, the environment, and human health. Polyhydroxyalkanoates (PHAs) are natural biodegradable microbial polymers with a promising potential to replace synthetic plastics. This research is focused on devising a sustainable approach to produce PHAs by a new microbial strain using untreated synthetic plastics and lignocellulosic biomass. For experiments, 47 soil samples and 18 effluent samples were collected from various areas of Punjab, Pakistan. The samples were primarily screened for PHA detection on agar medium containing Nile blue A stain. The PHA positive bacterial isolates showed prominent orange–yellow fluorescence on irradiation with UV light. They were further screened for PHA estimation by submerged fermentation in the culture broth. Bacterial isolate 16a produced maximum PHA and was identified by 16S rRNA sequencing. It was identified as Stenotrophomonas maltophilia HA-16 (MN240936), reported first time for PHA production. Basic fermentation parameters, such as incubation time, temperature, and pH were optimized for PHA production. Wood chips, cardboard cutouts, plastic bottle cutouts, shredded polystyrene cups, and plastic bags were optimized as alternative sustainable carbon sources for the production of PHAs. A vital finding of this study was the yield obtained by using plastic bags, i.e., 68.24 ± 0.27%. The effective use of plastic and lignocellulosic waste in the cultivation medium for the microbial production of PHA by a novel bacterial strain is discussed in the current study.

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Nasir, Kiran, Rida Batool, and Nazia Jamil. "Scale-Up Studies for Polyhydroxyalkanoate and Halocin Production by <i>Halomonas</i> Sp. as Potential Biomedical Materials." Journal of Biomimetics, Biomaterials and Biomedical Engineering 56 (May 20, 2022): 49–60. http://dx.doi.org/10.4028/p-yqf2wv.

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Polyhydroxyalkanoates (PHA) are the biomaterials isolated naturally from bacterial strains. These are present in granules and accumulated intracellularly for storage and energy uptake in stressed conditions. This work was based on the extraction of polyhydroxyalkanoates from haloarchaeal strains isolated from samples of a salt mine and Halocin activity screening of these isolates. For the screening of polyhydroxyalkanoates, Nile Blue and Sudan Black Staining were performed. After confirmation and theoretical determination, polyhydroxyalkanoates extraction was done by sodium hypochlorite digestion and solvent extraction by chloroform method in combination. Polyhydroxyalkanoates production was calculated along with the determination of biomass. Halocin activity of these strains was also screened at different intervals. Isolated strains were identified by 16S RNA gene sequencing. Polyhydroxyalkanoates polymer was produced in form of biofilms and brittle crystals. Halocin activity was exhibited by four strains, among which confirmed halocin activity was shown by strain K7. The remarkable results showed that polyhydroxyalkanoates can replace synthetic plastics which are not environment friendly as they cause environmental pollution – a major threat to Earth rising gradually. Therefore, by switching to the use of biodegradable bioplastics from the use of synthetic plastics, it would be beneficial to the ecosphere.

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Matsuo, Tomonori, Takashi Mino, and Hiroyasu Sato. "Metabolism of Organic Substances in Anaerobic Phase of Biological Phosphate Uptake Process." Water Science and Technology 25, no. 6 (March 1, 1992): 83–92. http://dx.doi.org/10.2166/wst.1992.0115.

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Biochemical mechanisms of anaerobic uptake of organic substrate by anaerobic-aerobic activated sludge were investigated experimentally. As the organic polymers stored in the cell, 3H2MB and 3H2MV were newly identified besides PHB and PHV. Conceptual pathways for the formation of PHA (polyhydroxyalkanoates) were postulated. It was suggested that the conversion of glycogen into PHA should be important for the mechanisms of biological excess phosphate removal.

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Licciardello, Grazia, Antonino F. Catara, and Vittoria Catara. "Production of Polyhydroxyalkanoates and Extracellular Products Using Pseudomonas Corrugata and P. Mediterranea: A Review." Bioengineering 6, no. 4 (November 14, 2019): 105. http://dx.doi.org/10.3390/bioengineering6040105.

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Some strains of Pseudomonas corrugata (Pco) and P. mediterranea (Pme) efficiently synthesize medium-chain-length polyhydroxyalkanoates elastomers (mcl-PHA) and extracellular products on related and unrelated carbon sources. Yield and composition are dependent on the strain, carbon source, fermentation process, and any additives. Selected Pco strains produce amorphous and sticky mcl-PHA, whereas strains of Pme produce, on high grade and partially refined biodiesel glycerol, a distinctive filmable PHA, very different from the conventional microbial mcl-PHA, suitable for making blends with polylactide acid. However, the yields still need to be improved and production costs lowered. An integrated process has been developed to recover intracellular mcl-PHA and extracellular bioactive molecules. Transcriptional regulation studies during PHA production contribute to understanding the metabolic potential of Pco and Pme strains. Data available suggest that pha biosynthesis genes and their regulations will be helpful to develop new, integrated strategies for cost-effective production.

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Ekere, Itohowo, Brian Johnston, Fideline Tchuenbou-Magaia, David Townrow, Szymon Wojciechowski, Adam Marek, Jan Zawadiak, et al. "Bioconversion Process of Polyethylene from Waste Tetra Pak® Packaging to Polyhydroxyalkanoates." Polymers 14, no. 14 (July 12, 2022): 2840. http://dx.doi.org/10.3390/polym14142840.

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Presented herein are the results of a novel recycling method for waste Tetra Pak® packaging materials. The polyethylene (PE-T) component of this packaging material, obtained via a separation process using a “solvents method”, was used as a carbon source for the biosynthesis of polyhydroxyalkanoates (PHAs) by the bacterial strain Cupriavidus necator H16. Bacteria were grown for 48–72 h, at 30 °C, in TSB (nitrogen-rich) or BSM (nitrogen-limited) media supplemented with PE-T. Growth was monitored by viable counting. It was demonstrated that C. necator utilised PE-T in both growth media, but was only able to accumulate 40% w/w PHA in TSB supplemented with PE-T. Only 1.5% w/w PHA was accumulated in the TSB control, and no PHA was detected in the BSM control. Extracted biopolymers were characterised by nuclear magnetic resonance (NMR), Fourier-transform infrared (FTIR) spectroscopy, electrospray tandem mass spectrometry (ESI-MS/MS), gel permeation chromatography (GPC), and accelerator mass spectrometry (AMS). The characterisation of PHA by ESI-MS/MS revealed that PHA produced by C. necator in TSB supplemented with PE-T contained 3-hydroxybutyrate, 3-hydroxyvalerate, and 3-hydroxyhexanoate co-monomeric units. AMS analysis also confirmed the presence of 96.73% modern carbon and 3.27% old carbon in PHA derived from Tetra Pak®. Thus, this study demonstrates the feasibility of our proposed recycling method for waste Tetra Pak® packaging materials, alongside its potential for producing value-added PHA, and the ability of 14C analysis in validating this bioconversion process.

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Mitra, Ruchira, Hua Xiang, and Jing Han. "Current Advances towards 4-Hydroxybutyrate Containing Polyhydroxyalkanoates Production for Biomedical Applications." Molecules 26, no. 23 (November 29, 2021): 7244. http://dx.doi.org/10.3390/molecules26237244.

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Polyhydroxyalkanoates (PHA) are polyesters having high promise in biomedical applications. Among different types of PHA, poly-4-hydroxybutyrate (P4HB) is the only polymer that has received FDA approval for medical applications. However, most PHA producing microorganisms lack the ability to synthesize P4HB or PHA comprising 4-hydroxybutyrate (4HB) monomer due to their absence of a 4HB monomer supplying pathway. Thus, most microorganisms require supplementation of 4HB precursors to synthesize 4HB polymers. However, usage of 4HB precursors incurs additional production cost. Therefore, researchers have adopted strategies to reduce the cost, such as utilizing low-cost substrate as well as constructing 4HB monomer supplying pathways in microorganisms. We herein summarize the biomedical applications of P4HB, the natural producers of 4HB polymer, and the various strategies that have been applied in producing 4HB polymers in non-4HB producing microorganisms. It is expected that the readers would gain a vivid idea on the different strategic developments in the field of 4HB polymer production.

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Journal articles on the topic 'Polyhydroxyalkanoates (PHA)'

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